Field of the Invention
Embodiments of the present invention relate to a touch screen device and a method of driving the same.
Discussion of the Related Art
Recently, various input devices such as mouse devices, trackballs, joysticks, digitizers, etc. are being used for providing an interface between users and home appliances or various information communication devices. Therefore, the demands for input devices which are convenient and simple and reduce the number of malfunctions are progressively increasing. In order to satisfy the demands, touch screen devices which enable a user to input information by directly touching a screen with a finger, a pen, or the like have been proposed. The touch screen devices are input devices that are conversationally and intuitively manipulated by merely touching a button displayed by a display unit with a finger, and thus, are easily used by men and women of all ages. Therefore, the touch screen devices are being widely applied to various devices, for example, portable display devices such as smartphones, tablet personal computers (PCs), portable multimedia players (PMPs), etc.
When a touch screen device is implemented in an in-cell type where the touch electrodes are provided in a display panel that displays an image, the touch electrodes may be disposed adjacent to pixel electrodes of pixels of the display panel and a plurality of driving lines connected to the pixels. Parasitic capacitances are formed between the touch electrodes and pixel electrodes and the driving lines, and finger capacitances are formed between the touch electrodes and a finger or a pen of a user. That is, a parasitic capacitance and a finger capacitance are formed in a touch electrode which is touched, but only a parasitic capacitance is formed in a touch electrode which is not touched. There is a difference between an electrical charge charged into each of a parasitic capacitance and a finger capacitance, which are formed in a touch electrode which is touched, and an electrical charge charged into a parasitic capacitance formed in a touch electrode which is not touched, and the touch screen device may determine which of the touch electrodes is touched, based on the difference.
However, a size of a parasitic capacitance is far greater than that of a finger capacitance. Therefore, a difference between an electrical charge charged into each of a parasitic capacitance and a finger capacitance, which are formed in a touch electrode which is touched, and an electrical charge charged into a parasitic capacitance is formed in a touch electrode which is not touched is very small. That is, a difference between a voltage sensed from a touched touch electrode and a voltage sensed from an untouched touch electrode is small. As a result, an accuracy of touch sensing is reduced.